Caching Proxy is a caching technique implemented in a proxy device, e.g., a proxy server. The caching proxy is used widely in Internet for improving Hyper-Text Transfer Protocol (HTTP) response time. All the HTTP requests from clients are transferred to a caching proxy device. If an HTTP request hits the cache of the caching proxy, the caching proxy device provides the cached content as a response to the HTTP request. Otherwise, if the HTTP request does not hit the cache, i.e. misses the cache, the caching proxy device send the HTTP request to a web server or a parent proxy server and receives an HTTP response therefrom. The caching proxy device caches the HTTP response and sends the HTTP response to the client.
If the content corresponding to the HTTP request exists among the contents cached by the caching proxy, this is expressed by “it hits the cache.” Otherwise if the content corresponding to the HTTP request does not exist among the contents cached by the caching proxy, this is expressed by “it misses the cache.”
If a content which is large in size but only a specific part of which is used frequently, it is inappropriate and inefficient to cache the whole content. For example, there may be a motion picture content of which only the starting part is played more frequently than the rest part. Also, if a 10-minute motion picture has an important scene in the duration of 5:30˜6:00, the corresponding part is likely to be accessed frequently. There is therefore a need of a method for solving the above problem.